Wireless signaling system



April 14, 1931. F GERTH ET AL 1,800,996

' WIRELESS S IGNALING SYSTEM .Filed Dec. 21, 1926 @gni g Fwl|n...^.n|\\\h..n| l UWWHUUWHH HHHHmHHHlHn w* Y/Upeflzfe HHIHHHHHHHHI\am'e Mada/@WWW lummuumuu m @wif @i aufefz'de f ii'egzleflfy V45 siredfrequencies may pass Patented Apr. 14,y 1931 Y' UNITED STATES PATENTOFFICE FELIX GERTH, F BERLIN-TEMPELHOF, AND FRITZ GUTZMANN, OF BERLIN- vCHARLOTTENBURG, GERMANY WIRELESS SIGNALING SYSTEM Application ledDecember 27,1, 1926, Serial No. 156,095, and in Germany December 24,1925.

Our invent-ion has reference broadly to Wireless signaling systems andis more particularly intended to provide means for reducing undesiredoscillations such as higher i; harmonics or side frequencies and otherinterferingy frequencies in wireless signa-lingl circuits.

Our invention finds particular application in such cases wheredisturbing frequencies l are present which are more or less symmetricalto the operatingfor signaling frequency and which are known in the artasside-fre-v quencies. Such frequencies occur especially in systemscomprising a high-frequency generatorof afundamental frequency incombination with one or more'iron-cored high-frequency transformers. Ithas become very well'known in the art of wireless signaling to eliminateundesired oscillations by the employment of intermediary circuits,rejector and acceptorfcircuits, filters and the like.

According to our invention we also make use of the working of rejectorand acceptor circuits vand our invention presents a novel V combinationthereof inv providing several paths in connection with a signalingcircuit, each' path consisting of an acceptor circuit tuned to one ofthe undesired frequencies andtherefore presenting'zero impedance forthis particular frequency and whereby the tuning of the several acceptorcircuits is so adjusted that in their resultant action with respect tothe operating (signaling) frequency they form' a rejector circuit forthe latter and thus' prevent the signaling frequency from entering theby-pass and force 1tback or reject it Vinto circuit portions to beactively employed in the system forsignaling purposes. The effectiveimpedance of 4.6 the by-pass is then increased in value for theparticular signaling frequency, whereby the signalingfrequency isconfined to the signaling circuit and the by-pass is rendered opaque tothe signaling frequency, while the undefreely thru the transparentacceptor circuits constituting the elements .of the rejector circuitarrangement of our invention.

Our invention will be more clearly understood by the following detaileddisclosure and specific example in connection with ironcoredhigh-frequency transformer systems reference being taken to theaccompanying drawings, in which Fig. 1 is a wiring diagram showing aportion of a signalng circuit with the circuit of our inventionassociated therewith, and of which Figure 2 is a wiring diagram of aniron-cored frequency transformer system with several circuits of ourinvention associated therewith, while Figures 3 to 4 inclusive areillustrative curves making clear the working principles underlying thehighlfreqFuency signaling system as represented y ig. 2.

Referring more particularly to Figure 1 u of the drawings the inventionis shown applied to an antenna ground system indicated by referencecharacters 1 and 2. Coupling inductance 3 and tunable loading coil 4 areincluded into this circuit forming the usual tuned oscillatory system.Preceding this antenna circuit is an intermediary circuit composed bycoupling inductances 5 and 6, capacity 7 and tuning inductance 8. Acoupling inductance 9 imparts to the inter- 75 mediary circuithigh-frequency oscillating currents from a generating system of an kindwell-known in the art and not indicated in the drawing for simplicitysSake. VIn the case the circuit relates to a receiving system go theinductance 9 leads to a detector or amplification circuit. Acceptorcircuits composed by inductances 10 and 12 and capacitiesll and 13respectively and being tuned each to one undesired frequency of the'signaling frequency and therefore presenting zero impedance forsameserve as a by-pass to such frequencies. The one acceptor circuit e.'g.10, 11 then presents a resultant capacitive reactance 14 for the sig- 90naling frequency and the other 12, 13 a resultant inductive reactancev15 for same or vice versa, which resultant reactances are indicated inthe drawing rby dotted lines. The values of this capacitive andinductive resulting reactances 14 and 15 respectively are dependent ofthe relation of the capacitive reactances 11 and 13 of the acceptorcircuits to their inductive reactances 10 and 12, respectively, as .forthe tuning of the acceptor v100 lying at either side 35 Y so chosen andadjusted,

circuits there is only necessary a distinct product of their capacityand inductance (frequency f being equal as is well known to `wherein 'Lis the inductance and C the capac-A ity of a tuned circuit) theserelationsmaybe reactances "14 and`15 respectively in vrespect to thesignaling frequency form in their combined action a rejector circuitlfor :this latter forcing it thereby into the portions of the Y circuitssystem activelyeinployed for signaling e. g. thru coupling coil 5inthecase of a transmitter or thru coupling coil l6 in the case of areceiver. kThus theA signaling .frequency isprevented from Vpassinginpart thru the bypass' circuit, yand losses of the active signalingenergy V involved Vby such bypassing are Y eliminated.

Referringnow moreparticularly to Figure 2 of the drawing, similarreference' characters tothat in Figure ments. I transformers .with ironcores 18 and 19 and windings 2O and 21 respectively. The transformer"'16 is energized -by an alternating current source ofa fundamentalfrequency e. g. a high-frequency generator 22, and the transformer A,17'forming a second 'transforinationl step is energized bythe firsttransformer 1 6, the two cascade 'connection whichis generally employe'dwhen carrying out a very Vhigh-fre- The further elethe system are the I23 and 24 and they capacities :25' and 26 of the transformeroutqnencytransformation. ments vforming part'of tuning self-inductancesputlcirciiits respectively 4called alsormultipli- Y cation or impulseVcircuits as will be understood the following detailed deSCriptionof theworking :of the system. Y Y

H'-Ilie'iron-core sty ucture 'of the transformer is given so littleiron, that it is already saturise vto free damped osclletiontrains n,theI

natural frerpaency of the `impulse circuit. 'llhese `oscillation ftrains, .because of their Tena successen present a continuousoscillation Lwave such as'represented bythe Fig: ure of the drawings.The oscillations die out tol a; certain extent to be increased to theirthat the resultant yemployed (e.

Y 1 refer to similar ele-v 16 and 1'? re resent static frecuency` Y P itransformers thus being arranged .inV

(fundamental) .al-pv original value periodically when a new vtensionpeak occurs. By reducing the damping factor of the impulse circuit tothe smallest value possibly by utilizing a small-capacity and a largeinductance the dying out of the single Wavetrains .maybe minimizeditosuch a-n ext-ent ythat an almost sustained .or undamped high-frequencycurrent wave is obtained.u l`However; especially when very"high-frequencies Vare Vto be generated i. e.

when veryYYlarge transformation ratios are g. the seventeenth of afundamental frequency) no purely sinusoidal os- ,cillationshbut of ashape-more or less ,similar to that represented by Figure 3 will beobtained. Such :a curve according to Fig. 3 equals a modulatedhigli-frequency current and may therefore be resolved into the .carrierfrequency and a number lof frequencies Y lying symmetrically :at :bothsides .of same and'known as side-.band frequencies. For

instance an oscillation amplitudevariation or in technical languagebeingl sinusoidally lmodulated as represented by c in Fig-ure 4l mayberesolved into oscillations of constant Vamplitudes .consisting of thecarrier frequency c and quencies b and d lying symmetrically vat bothsides ofthe carrier frequency. If the am# pl-itude oftheoscillationsdoes not vary ac-r cording to Aa 1puresine law but according to anirregular'periodical law such as e. g.k is

shown by Figure 3, thisvariation may 'be dissolved at V.its part.according to Fouriers theorem. into a plurality of pure sine variationstheresult beingiof the presence of not only one, as in case of Figures,but cfa number` of pairs of symmetrical vside-frequencies. rlhus insignaling systems employingfrequency transformation vapparatus' 'of' thecharacter described, one or more pairs of side frequencies may occurwhich are `radiated likewise the signaling frequency by a radiatingsystem and may cause interference in the receiving apparatus. Byemploying circuit arrangements in accordance with our invention thesedisturbing side-frequencies may be prevented k,from being radiated andthus interference Ydisturbances substantially eliminated. Referring oncemore toliigigureY 2 yoi-i the one hand and the self-inductance 29 andthecapacity on lthe other hand are so adjusted' that the circuit 27 28is-tuned to one of a pair of side-frequencies presenting' zero impedancefor same and equally circuit 29, 30ris-tuned to the otherside-frequencyhaving sinusoidal side-band fre ies iis the self-inductance 271 and thecapacity 28 f ish lying symmetrically with respect tothe sig f nalingvfrequency and presenting Yzero iinpedance forsame. :The result is thatof only' the lohmic resistance for these. corresponding sideffrequenciesremain inv both acceptor circuits 27 28 and 29, 30 respectively."V Thewhole circuit 27', 28, 29, 30 formsafi'ejector circuit `for the'signaling frequency, by ad'- f justing a suitable relation ofinductance 27 to capacity 28 and inductance 29 to capacity 30respectively in the same manner as described with reference to Figure l.

The circuit associated in accordance with our invention may also bearranged in a multiple way for the elimination of more pairs ofdisturbing frequencies or for increasing the effect to be obtained.According to Figure 2 an eliminating circuit arrangement is arrangedalso in the impulse circuit of the second frequency transformer, 31 and33 being the inductances and 32 and 34 the capacities of its acceptorcircuit elements respectively. placed between the multiplication circuitof the second transformer stage and the antenna system may contain acircuit arrangement according to our invention in conformity with thesignaling system represented by Figure l.

We may also provide three or more acceptor circuits by-passing three ormore undesired frequencies and forming in their combined action arejector circuit for the signaling frequency.

When dealing with frequency transforming systems as represented byFigure 2 it is necessary, according to a further object of ourinvention, to provide an eliminating circuit arrangement already in thefirst impulse circuit as the side-frequencies existing in this latterwould be multiplied by the following transformation step andside-frequencies in the second impulse circuits would be so numerous andso close to the signaling frequency, that not even rejector circuitswith the highest selectivity would be able to reduce them to asufficient degree.

The principle of operation of our invention as pointed out may beemployed with any sort of signaling circuits especially those whereundesired frequencies may be combined into groups enabling theembodiment of a circuit arrangement according to our invention andwhile'we have described our invention in certain specific embodiment, itwill be understood that we intend no limitations other than are imposedby the scope of the ap ended claims.

aving thus described our invention, what we claim and desire to beysecured by Letters Patent of the United States is:

l. In a wireless signaling system, an ironcored frequency transformerhaving input and output circuits, means for applying a fundamentalfrequency to the input circuit of said transformer, means whereby asignaling current whose frequency is a multiple of said fundamentalfrequency flows in said output circuit, said last means beingresponsible also for a plurality of currents of undesired sidefrequencies produced besides said signaling frequency, a signalingcircuit connected to said output circuit, a second Also the intermediarycircuitv circuit comprising ua plurality ofl acceptor, circuitsconnected to said output circuit, one a'cceptorcircuit being providedfor each of objectionable side frequencies for by-passing these sidefrequencies from said signaling circuit, said acceptor circuits being sotuned that in their combined action they constitute arejector circuitfor the signaling frequency.

2. In a wireless signaling system, a plurality of iron-coredfrequency'transformers arranged in cascade connection, each having inputand output circuits, means for applying'a. fundamental alternatingcurrent to the input vcircuit of one of said frequency transformers,means whereby a signaling current the frequency of which is a multipleof said fundamental frequency flows in said output circuits, there beingalso produced objectionable side-frequencies which flow in saidcircuits, circuit arrangementsv associated with said transformer outputcircuits, each comprising a plurality of acceptor circuits, one for eachof a pair of said objectionable side frequencies whereby suchobjectionable lfrequencies are by-passed from portions of the circuitVcarrying the active signaling currents, said acceptor circuits for saidside frequencies being so tuned that in their combined action theyconstitute rejector circuits for the respective active signalingfrequencies in said transformer output circuits.

3. In a wireless signaling system, a plurality of iron-cored frequencytransformers arranged in cascade connection, each having an input andoutput circuit, means for applying a fundamental frequency to the inputcircuit of one of said frequency transformers, a signaling circuit,means whereby signaling and other objectionable frequencies of saidfundamental frequency flow in the output circuits of said frequencytransformers and a circuit arrangement associated with the outputcircuit of said first frequency transformer comprising acceptor circuitfor each of said objectionable frequencies, whereby said frequencies areby-passed from portions of the circuit that are 1n operative relationwith a following active signaling circuit, the tuning conditions of saidacceptor circuits being so adjusted that in their combined action theyconstitute a rejector circuit for the multiplied frequency in the outputcircuit of said first frequency transformer.

4. In a signaling system, a high frequency generator in which aplurality of objectionable side frequencies occur besides a definitesignaling frequency, a signaling circuit connected to said generator,means for suppressing sald side frequencies from sald signaling circuitcomprising a plurality of acl" ceptor circuits, one for each of saidside frequencies, arranged in by-pass relationship in respect to saidsignaling circuit, the tuning conditions of said acceptor circuits beingso adjusted that in their combined action they ting saidsignalingfrequencies.

constitute arej'ector circuit for the signaling frequency and atransmitting Ysystem., connected to said signaling circuiti fortransmit- 5. In combination with a high frequency i' generator in whichbesides the signaling frequency disturbing side frequenciessymmetrically to the signaling frequency are generated, a generatorcircuit, a transmitter circuit connectedV to said generator circuit fortrans-l mitting said signaling frequency, means for suppressing saidside frequencies from said transmitter circuit comprising a pair ofacceptor circuits tuned to a pair of symmetric side frequencies and.-arranged inA by-pass relationship in Vrespect to said transmittercircuit, the tuning conditions of said acceptorV circuits being soadjusted that in their combined/action they constitute a rejectorcircuit for the signaling frequency and a transmitter circuit connectedto said generator circuit for transmitting said frequencies. Y

' 'In testimony whereof We have aiiixed our signatures. s Y

f FELIX. GERTH.

FRITZ GUTZMANN.

